Toss the cabbage and carrots with salt together in a colander set over medium bowl. Let it stand until cabbage wilts, at least 1 hour and up to 4 hours.

Dump the wilted cabbage and carrots into the bowl. Rinse thoroughly in cold water; ice water if serving immediately. Pour the vegetables back into the colander, pressing but not squeezing them to drain. Pat dry with paper towel.

Pour the cabbage and carrots back into the bowl. Add the onion, mayonnaise and vinegar; toss to coat. Season with pepper. Cover and refrigerate until ready to serve.

Tip

The first 2 steps are not absolutely necessary, however they add an added degree of crunchiness to the coleslaw. Also, if not done, the cabbage will weep making the salad "soupy".